Manufacture of laminated core inductors



July 9, 1963 o. H. BIGGS ETAL MANUFACTURE OF LAMINATED CORE INDUCTORS Original Filed Oct. 1, 1958 15 Sheets-Sheet l INVENTORS O. H. BIGGS T. WROBLEWSKI D R. DAYTON Y 6M ATTQRNEY July 9, 1963 o. H. BIGGS ETAL 3,095,563

MANUFACTURE OF LAMINATED CORE INDUCTORS Original Filed Oct. 1. 1958 15 Sheets-Sheet 2.

INVENTORS t 0.H. BIGGS 14-15 T. WROBLEWSKI D. R. DAYTON BY ATTORNEY Jlily 9, 1963 o. H. B1 s ETAL 3,096,568

MANUFACTURE OF LAMINATED CORE INDUCTORS Original Filed Oct. 1, 1958 15 Sheets-Sheet 3 ZFEED INVENTORS O. H. BIGGS T. WROBLEWSKI DR. DAYTON ATTORNEY July 9, 1963 O. H. BIGGS ET AL 3,096,568

MANUFACTURE OF LAMINATED CORE INDUCTORS Original Filed Oct. 1, 1958 RETURN l5 Sheets-Sheet 4 l INCREMENT NCREMENT OPERATE RETUR RETURN OPERATE OPERATE OPERATE RETURN FEED 3 OPERATE FEED FEED

OPERATE START IMPULS COUNT BEND RETURN CUT OPERATE CLAMP COUNT COUNT-OUT ZERO loda 1.2.3 FEEDS AND 'IINCREMENTSJERO AND INCREMENT CLUTCHES. CUTTER. ETC.. FOR

ZERO CYCLE av WW ATTORNEY July 9, 1963 O. H. BIGGS ETAL MANUFACTURE OF LAMINATED CORE INDUCTORS Original Filed Oct. 1, 1958 15 Sheets-Sheet 5 INVENTORS O. H. BIGGS T. WROBLEWSKI CPO S 2p. R. DAYTON ATTORNEY July 9, 1963 o. H. BIGGS ETAL 3,096,568

MANUFACTURE OF LAMINATED CORE INDUCTORS Original Filed Oct. 1, 1958 15 Sheets-Sheet 6 BYW.WW

ATTORNEY July 9, 1963 H. BIGGS ETAL 3,096,563

MANUFACTURE OF LAMINATED CORE INDUCTORS Original Filed Oct. 1, 1958 15 Sheets-Sheet 7 INVENTORS o. H. areas 1 I T. WROBLEWSKI I 0. R. DAYTON I aYe-fw- WW ATTORNEY July 9, 1963 O. H. BIGGS ETAL MANUFACTURE OF LAMINATED CORE INDUCTORS Original Filed Oct. 1, 1958 15 Shets-Sheet 8 -3OQQOO OOOGOOOOOJO-OQO INVENTORS O. H. M668 T. WROBLEWSKI D. R. DAYTON av gjw.

' TT RNEY u y 9, 1 o. H. BIGGS ETAL 3,

MANUFACTURE OF LAMINATED CORE INDUCTORS Original Filed Oct. 1, 1958 15 Sheets-Sheet 9 ATTORN EY July 9, 1963 Original Filed 001;. 1, 1958 ma w o. H. BIGGS ETAL 3,096,568

MANUFACTURE OF LAMINATED CORE INDUCTORS 15 Sheets-Sheet 10 INVENTORS O. H. BIGGS T. WROBLEWSKI D. R. DAYTON ATTORNEY July 9, 1963 Y o. H. BIGGS ETAL 3,096,568

MANUFACTURE OF LAMINATED CORE INDUCTORS I Original Filed Odt. 1, 1958 l5 Sheets-Sheet 1-1 'INVENTORS 0. H. GS T. WROBL sm ATTORN EY July 9, 1963 Original Filed Oct. 1, 1958 Cl FL BIGKSS E1UAL MANUFACTURE OF LAMINATED CORE INDUCTORS INVENTORS o. H. 81665 T. WROBLEWSKI D. R. DAYTON ATTORNEY July 9, 1963 O. H. BIGGS ETAL MANUFACTURE OF LAMINATED CORE INDUCTORS Original Filed Oct. 1, 1958 15 Sheets-Shet 15 INVENTORS O. H. BIGGS T. WROBLEWSKI BY & D. R. DAYTON ATTORNEY,

July 9, 1963 o. H. BIGGS ETAL 3,096,568

MANUFACTURE OF LAMINATED CORE INDUCTORS Origipal Filed Oct. 1. 1958 15 Sheets-Sheet 14 INVENTORS ,0. H. BIGGS Tw' WROBLEWSKI R. DAYTON 7 1g1 17a BY G ATTORNEY July 9, 1963 o. H. BIGGS ETAL 3,096,568

MANUFACTURE OF LAMINATED CORE INDUCTORS Original Filed Oct. 1, 1958 15 Sheets-Sheet 15 INVENTORS ATTORN EY O.H. BIGGS T. WROBLEWSKI ?g l BY S: DAYTON United States Patent Original application Oct. 1, 1958, Ser. No. 764,588. Di-

vided and this application Nov. 2, 1959, Ser. No.

7 Claims. (Cl. 29155.61)

This invention is concerned with electromagnetic in ductors of the laminated core type, and particularly with improvements in methods of manufacturing these inductors and machinery for fabricating their cores. The present application is a division of Ser. No. 764,588, filed October 1, 1958, in behalf of the same inventors.

Electromagnetic inductors, in the form of transformers or inductive reactors, are among the more generally used of electrical and electronic components; and their size, weight, and cost are critical factors in the design of systems and equipment.

The size and weight problem is due principally to the metal core which is used to provide a relatively low reluctance path for the electromagnetic field produced by the inductive coils. It has been the custom to alleviate this difiiculty to some extent by resorting to a laminated core construction which avoids the eddy currents affecting the efficiency of a solid core and therefore requires less total mass to provide a given flux conductivity.

Laminated cores have generally been made in three types characterized by the configuration of their component laminations. The least expensive to manufacture is the E-configuration core which is assembled by stacking individual E-shaped stampings one upon the other to achieve the desired mass of metal. Preformed inductive windings are then placed \around one or more legs of the E, and the magnetic circuit is completed by closing the open side with an I-shaped bar. Although this method of assembly has the merit of being relatively inexpensive, it demands a heavy premium in size and weight because of the inherent inefiiciency resulting from the flat stamping of an E-shaped member having a different direction of metal grain, as far as magnetic flux is concerned, in its base leg than it has in its arms. This causes an uneven flux through the stamping with resulting design problems and necessity for extra mass to achieve a desired total flux conductivity.

A second type of transformer core is designated as the C-configuration. It is so-called because the individual llaminations are in the shape of the letter C with flat top and bottom legs. A complete core is formed by butting .two C laminations together, or closing the end of a C with an I member, after inductive windings have been placed around selected legs of the C or the I. The individual laminations of the C may comprise flat stampings, as referred to above in connection'with the E-configunation, or they may be cut into lengths and bent to the C-configuration with a series of laminations stacked one around the other to form a core.

Cores of this latter type, i.e. the bent C, have been known in the art at least since the issue of British Patent 7,856 of 1889. They overcome the difficulties associated with the disparity of grain discussed with reference to the stamped E-laminations, but are difficult to fabricate and assemble because, in order to permit stacking, each side of each successive lamination within the stack must increase in dimension by an amount determined by the thickness of the stock material.

A third type of core is the so-called toroid which is formed from a continuous spiral of strip metal. This type has superior flux characteristics because of its continuous and unidirectional flux path but it is relatively expensive and difiicult to fabricate, except for inductors whose windings have few turns.

The industry has long sought a manufacturing technique which would provide the flux efliciency of the toroid or bent C and yet be as amenable to manufacture as the stamped E- or C-configurations.

US. Patent No. 2,477,350 describes one method of providing a core of the bent C type which is fabricated by stacking an assembly of strips of magnetic material pre-cut to progressively varying lengths and then bending the entire assembly to the desired core configuration with the aid of a special jig and press combination. The resulting core would appear to enjoy relatively high flux conductivity, but the method of making it is difficult to practice and inherently limited for satisfactory operation to a relatively few number of laminations.

Another approach is shown in Acly Patent 1,935,426. Here, a basic toroid configuration is provided by winding a strip of core material around a form. The core is then cut in one or two places to permit it to be inserted through the center window or opening of a preformed winding and reassembled as a complete inductor. Again, there is relatively high flux conductivity but the disadvantage of at least partially destroying the effect of annealing the core material in the area of the cut so that this requirement of the magnetizing process must best be performed as a separate step for each core after cutting instead of in the more efficient manner as an adjunct of the rolling of the strip material. Also, the individual laminations of each core must be separated after the cutting process and individually inserted through the core by hand in an intricate pattern of alternate reversal of original position to provide an overlap at the joints to provide optimum flux and hold the assembly together.

These fabrication and assembly techniques are representative of the present state of the art and have resulted in manufacturers of transformers and other inductors in large quantity lots being for the most part forced to adopt the relatively inefiicient E configuration as their commercial standard because it is the one best suited to economic production techniques and enables them to supply the product at a price the industry can afford.

This practice, however, has not been entirely satisfactory. As a practical necessity, the manufacturer has been forced to limit his product line to a number of specific sizes and ratings, and his selling price must carry the burden of inventory of the stamped laminations of all sizes that he or his supplier must have on hand to provide prompt response to orders. Also, the user must pay a premium for special design and construction; or else, accept the extra size, weight and cost of the relatively inefficient E-configuration. This burden is further aggravated because, as a practical matter, the only unit available from a stock line to satisfy a given requirement will most generally be one with a rating in excess of the specific need.

Another anomaly of the present state of the art of manufacturing laminated core inductors is that, within practical ranges of size, the cost of individual units goes up as size goes down because of the fabrication difiiculties involved.

Accordingly, a principal objective of the present invention is to provide a method and machinery for the manufacture of laminated core inductors, such as transformers, reactors, etc, which will be less expensive from the viewpoint of dollar cost, as well as in weight and size, and more responsive to design requirements of special orders, than the techniques of the present state of the art.

Other objectives are to provide an improved method for manufacturing laminated core inductors and improved machinery for the fabrication of bent metal strips of progressive sizes suitable for the laminations of the cores of such inductors.

A more specific objective is to provide a manufacturing method and mechanism whereby laminated core inductors may be produced at a cost comparable to that of present E-configurations but with a flux efficiency comparable to the bent C and toroid types.

These and related objectives are accomplished in accordance with the present invention by a different approach to the problem of manufacturing cored inductors and fabricating the laminations which comprise their cores. This approach features feeding at a work station, from a source such as a roll of strip stock metal, a critical length of material for each dimension of each lamination. The strip is bent after each feeding operation to provide the desired configuration for the lamination and severed when the lamination has been completely formed. Also, the amount of material fed for corresponding dimensions of successive laminations is altered in increments measured by the thickness of the stock material so that successively formed laminations fit one to the other in a stack.

This manufacturing technique has the merit of making it possible to build up a core with any desired number of laminations instead of being limited to the capacity of the jig and press combination referred to previously. Also, the separate bending of the laminations makes possible a better fit of the laminations comprising the stack than when they are all bent together in a single operation and, consequently, a better flux characteristic. Moreover, the bending and cutting of the stock material in single thicknesses does not destroy the effect of previous annealing.

In one embodiment of the invention the separate prebent laminations are each of the bent C type with one arm of the longer than the other. With this design, when alternate laminations in the stack are turned so that the short side of succeeding laminations will be first on one side of the stack and then on the other, the result is a serrated edge along the butt ends of the assembled C. This 0 comprises a half core. With two half cores made in similar fashion, it is possible to match complementary serrations and fit them together to form a complete core providing a continuous magnetic circuit. Before this matching of serrations takes place, however, the inductive windings of one or more coils, which have been preformed in a separate operation, are placed over whatever leg or legs of the serrated half cores is required by the design of the inductor. Consequently, when the half cores are matched together, the complete inductor combination of core and windings is provided.

The machinery which is used to fabricate the individual laminations of the core comprises: a work station through which strip stock of lamination material is fed; a bend brake to bend the stock to the configuration of each lamination; a cutter to sever the laminations from the stock material; a feeding mechanism which moves the stock material through the work station in independently controllable measured lengths for each bending or cutting operation; and, means for causing these measured lengths to differ in increment equal to the thickness of the stock for each corresponding dimension of successive laminations so that these will be adapted to fit into or around one another.

This cutting and bending mechanism has automatic and adjustable control of the dimensions of successive laminations, and makes it possible to fabricate automatically the laminations of bent C type cores which have superior flux conductivity and are adapted to be fitted to preformed windings with an economy of labor and time. The windings of one inductor can be assembled to its core while the laminations of the next core are being automatically formed; and, since both the size and number of laminations can be changed as a matter of simple machine adjustment, it is possible to provide the exact mass of core required for any set of specifications. Thus, optimum inductor design is provided with a minimum of difficulty, and the only inventory of core material or laminations required is rolls of strip stock.

Other embodiments, modifications, and objectives of the invention will be apparent from the following description of a method of manufacture and a mechanism which have given satisfactory performance in the production of cored inductors, and reference to the accompanying drawings, wherein:

FIG. 1 is a perspective view of a single lamination adapted to be assembled into the core of an electromagnetic inductor;

FIG. 2 is a similar perspective of an assembled stack of laminations forming a half core;

FIG. 3 is a perspective of two half cores and the preformed windings of an inductor arranged for assembly into an integral unit;

FIG. 4 is a perspective of an assembled inductor;

FIG. 5 is a plan view of the work station and feed control of a lamination forming machine;

FIG. 6 is a plan view of feed and increment measurement controls for the mechanism of FIG. 5;

FIG. 7 is a functional block diagram of the mechanism of FIGS. 5 and 6;

FIG. 8 is a side elevation, partly in section, in the direction of arrow 8 in FIG. 6, of one of the feed control mechanisms;

FIG. 9 is a side elevation in the direction of arrow 9 in FIG. 6 of an increment operating mechanism and the control for setting the length of the initial lamination;

FIG. 10 is a rear elevation, in the direction of arrow 10 in FIG. 6, of an increment control mechanism;

FIG. 11 is a front elevation, in the direction of the arrow 11 in FIG. 6, of an increment control mechanism;

FIG. 12 is a sectional view, along the line 1212 in FIG. 5, of the bending and cutting mechanism at the work station;

FIG. 13 is a side elevation, partly in section, in the direction of arrow 13 in FIG. 5, of the bend brake operating mechanism;

FIG. 14 is a front elevation, partly in section, in the direction of arrow 14-15 in FIG. 5, of the clamp at the work station and its operating mechanism;

FIG. 15 is a front elevation, in the direction of arrow 14-15 of FIG. 5, of the cutter at the work station and its operating mechanism;

FIG. 16 is a diagrammatic representation of one of the operating racks of the machine along with it solenoid operated pneumatic prime mover and the switch contact by which it controls other operations in the machine;

FIG. 17a is a schematic diagram of part of the control system of the machine; and,

FIG. 17b is a similar schematic diagram of the remainder of the control system.

METHOD OF ASSEMBIJING A LAMINATED CORE AND INDUCTOR FIGS. l-4 show, in perspective view, the steps involved in assembling a laminated core and inductor, e.g. a transformer, after the manner of the invention.

Individual C-shaped laminations 20, each having a long arm 22, a short arm 24 and a base 26, are separately bent and cut from strip stock of magnetic material. The dimensions of the arms 22 and 24 and the base 26 are changed in successive increments or decrements equal to the thickness of the stock, for corresponding dimensions of successive laminations so that each succeeding one fits compactly around its predecessor to form a half core assembly 28. In effecting these changes the linear dimension of the base 26 of each lamination is altered by twice the thickness of the stock material and the linear dimension of each arm portion 22 and 24 is increased (or decreased) by an amount equal to a single thickness of the material so that the net effect of connecting two arms so extended, when two half cores are joined together, is to change the entire resulting structure by a linear dimension equal to twice the thickness of the stock material. Thus, when two half cores are so joined, the resulting fonrsided laminations will fit one within the other in a nested stack.

During the stacking of the half core 28, alternate laminations 20 are turned so that the long sides 22 and the short sides 24 are staggered to provide a serrated edge along their butt ends, as shown in FIGS. 2 and 3. Then, a pro-termed inductive winding 30 is put into position around an arm 22 or 24 of a half core 28 and the serrations of this half core are matched to complementary serration of another half core through the central opening or window of the winding 30 to provide a complete core 32 and transformer assembly 34.

PRINCIPAL PARTS AND GENERAL THEORY OF OPERATION OF LAMINATION FORMING MA- OI-IINE FIGS. 5 and 6, in combination, show a plan view of a machine for fabricating separate C-slhaped laminations 20, with size and base dimensions changing in controlled increments from one lamination to another.

In FIG. 5 a strip 36 of stock material is shown tfeeding through a work station 38. At this station, it passes under a die plate 40 having a bend surface 42 against which the material 36 is bent by a bend brake 44 (see FIG. 12). A cutter 46 is also provided to sever the bent stock from the strip between larninations. This cutter underlies the die plate 40 and is shown in FIGS. 12 and 15, but not FIG. 5. The length of sides 22 and 24 and base 26 or :the laminations 20 is determined in each instance by the length of stock fed through the work station 38 and across the die plate 40, for each bending or severing operation. This length of feed is measured by the degree of turn imparted to a feed roll 48 by its control shaft 50 (see FIG. 5).

As shown in FIG. 6, feed control shaft 50 is connected via coupling 52 to a feed control shaft extension 54 which is adapted to be turned by any one of a plurality (three are shown) of clutches 56. There is a separate clutch for each dimension of the laminations, e.g. sides 22 and 24 and base 26; and, each clutch is driven through a gear 58 by a rack 60. The degree to which each clutch 56 Will turn shaft 54 is controlled by the adjustable traverse of an increment control rack 62 driven by each clutch 56 through a gear 64. (See FIG. 8).

The traverse of each increment control rack 62 is adjustably controlled by the position of a stop nut 66 movable upon a threaded increment adjustment shaft 68. Shaft 68, as shown in detail in FIGS. 9 and 10, is turned by a clutch 70 through chain drive connection to an increment control shaft 72 which is in turn driven by an increment clutch 74. This clutch 74 is moved (see FIG. by a rocker 76 which has its stroke adjustably con trolled to correspond to the thickness of the stock material 36 by an increment limiting screw 78.

A zeroing motor 80 driving a zero chain 82 and zero clutches 84 are also provided to turn shafts 68 in order to screw stops 66 to the proper initial setting at the start of the series of laminations which are to comprise a core.

The prime movers for most of the mechanical motions of the machine are solenoid controlled pneumatic piston devices 86 (see FIG. 16) operated by a system of switches and relay controls shown schematically in FIGS. 17a and 17b.

The block diagram of FIG. 7 shows, in general outline, the manner in which this control system operates the machine to fabricate a three-sided lamination such as the C-shaped example shown in FIG. 1.

The starting operation 88 energizes the control system and initiates a cutting operation 90 to provide a reliably severed reference end of stock 36 to start the first 6 lamination. Operation of the cutter also causes the #1 'Feed 92 to measure the proper length of stock across die plate 40 at work station '38 for the first side, e.g. 22, of the lamination.

The #1 Feed, in turn, causes the bend operation 93 to bend the stock between the first side and the base 26. It also causes the 1 Increment Control 94 to move its rocker 76 and its associated increment control mechanism to adjust the position of its associated stop 66 and thereby provide for an incremental increase in the traverse of its rack 62 and a con-sequent increase in the degree of turn imparted to shaft 54 and in the length of stock measured out for the corresponding first side 22 of the next lamination.

Operation of the #1 Feed also initiates operation of the #2 Feed 96 which: measures out the stock material for the base 26 of the lamination; causes the bend brake 44 to make the bend between the base 26 and the other side 24; resets, i.e. returns, the prime movers of the #1 Feed and the #1 Increment Control to their original position, where they are then ready. to start their next respective operations; operates the #2 Increment Control 98; and, initiates operation of the #3 Feed 100.

The #3 Feed, in turn: measures out the stock for the other side 24 of the lamination; operates the #3 Incremcnt Control 102; returns the prime movers of the #2 Feed and #2 Increment Control; and, operates the cutter to sever the completed lamination from the strip stock and initiate the operating cycle for another lamination. The prime movers of the #3 Feed and #3 Increment Contr-ol are returned to operating position by the cutter and the -#1 Feed, respectively.

In addition to severing the completed lamination and initiating the operating cycle for fabrication of another lamination, the cutter also controls the operation of the counter 104 which, upon achieving the full count of the desired number of laminations, starts the Zero Operations 106a and 106b, which cycle all of the operating mechanisms to their proper position to start another series of laminations for another core, and also resets the counter 104.

DETAILED DESCRIPTION OF PARTS Work .S'tatzon.'Ihe work station '38 is shown in plan 'view in FIG. 5 and in section in FIG. 12. FIGS. 13, 14, and 15 are elevations of some of its component parts.

At this station, the strip of stock material 36 is fed across the under surface of a die plate 40 by feeding rollers 48 and associated mechanism which have been referred to above and will be described in more detail below. Guides 108 are provided to keep the stock material, which may be fed from a roll (not shown), centrgl of the guide plate 40 and within the area of a clearance groove 110 in its upper surface. The plate 40 is secured to the frame 112 of the machine by a hold-down support or bracket 114.

A take-up device 116 is also provided at the work station. This device comprises: a motor 118 supported by a pivot 1'20 attached to a structural member 122 of the framework of the machine; a roller mechanism 124, constantly driven by the motor 118 through a drive belt or chain 126 to assert a steady tension on the strip of stock material 36 urging it away from the feeding rollers 48 and across the die plate 40; and, a lifting lever 128 by means of which the entire assembly 116 can be raised to provide clearance for starting the stock material 36 through the work station 38 during preliminary set up of the machine. Normally, the assembly 116 is held by a spring, not shown, or gravity so that the rollers 124 are constantly in resilient engagement with the stock material 36. A gear .130 comprises part of the driving mechanism for the roller system 124.

Bend Braker.--The bending mechanism is shown: in plan View, in FIG. 5; in section, in FIG. 12; and, in elevation, in FIG. 13. Its principal component is a bend brake 44 having a substantially square cross section and adapted to be turned upon an :axis corresponding to its edge 44a and coinciding with the bottom edge of the forward or bending surface 42 of the die plate 40 (see FIG. 12). This turning action bends the stock material 36, which feeds through a throat 131 formed by the underside of plate 40 and a portion of the machine frame 112 adjacent the bend brake 44, over the bending edge 40a of die plate 40 and up against surface 42. FIG. 12 shows how a complete lamination 20 has been bent twice so that its first side 22 is turned back to overhang die plate 40. Clearance groove 1:10 is provided in case a dimension such as side 26 is so short that the bent-back side 22 will not clear the plate 40. As shown in FIG. 12, the three-sided lamination 20 has been bent after two successive feeding operations and then severed from strip 36 after a third feeding.

The bend brake 44 ismounted upon a shaft 132 which is coaxial with the bending line at the bottom of the bending surface 42 on die plate 40. This shaft 132 is attached at either end to gears 1134 which are driven by jack shaft gears. 136, attached to a jack shaft .138. One of these jack shaft gears, 136a, is in mesh with and driven by a rack 1'40 attached by a connector 142 to the piston 144 of a solenoid controlled pneumatic cylinder 146. The rack 140 is adapted to slide in a track 148 attached to the frame of the machine; and, an adjustable stop, in the form of a stud 150 threaded through a stop block 152 fixed to the track 148, is provided to limit its upward traverse. The limit of its downward traverse is determined by and adjustable setting of the cylinder 146.

Adjustment of this setting is accomplished with the aid of top and bottom cylinder support blocks 154 and 156 respectively. Top block 154 is fixed to a shaft 158 mounted parallel to the track 148. This shaft 158 is adjustable in a longitudinal direction by reason of its being threaded through a block 160, attached to the frame of the machine, and is held in adjustment by means of nuts 162 and 164 adapted to lock against block 169. Grooves 166 and 163 in the frame of track 148 provide clearance for blocks-1514 and 156, respectively, thereby making it possible to raise and lower the cylinder 144 by threading shaft 158 up or down in block 160. This increases, or decreases, the traverse of rack 140, i.e. the distance, from the top of piston 144 to the stop 150, and thereby controls the degree of turn imparted through the gears 136 and- 134 to bend shaft 132 and bend brake 44, an adjustment which is desirable to compensate for variation in the thickness of different stock materials 36.

Cutter.The cutting mechanism is shown in section in FIG. 12, and in elevation in FIG. 15. Its shearing action is accomplished by bringing a blade 46 across the cutting edge 170 of an insert 172 in the die plate 46. This insert also has a clamping surface which will be referred to in more detail below.

The cutter blade 46 is adjustable against the cutting edge 170 by a set screw 173 through the frame 112 of the machine and is attached to a slide 174 by means of an adapter plate 176. Slide 174 is movable between guides 178 and a filler or spacer 180 by the piston 182 of a solenoid controlled air cylinder 184 operating through a system of levers 186 mounted on a pivot 138 and connected to the slide 174 by a toggle 190, and to this piston 182 through a connector 192 and a slide 194 mounted in a track 196 attached to the main frame of the machine.

An adjustment for the height of the cutting blade 46 is provided by a threaded stud and lock nut combination 198 connected to the bottom arm of the toggle 190.

Clamp.The clamp 209 which holds the stock material 36 during the cutting operation is shown with its associated operating mechanism: in section, in FIG. 12; and, in elevation, in FIG. 14.

The clamping action is performed by forcing the clamp 200 against insert 172 in the top die plate 40. Clamp 200 is attached to a slide 202 mounted between the spacer 139 and a guide 264. Slide 292 is mounted on a link or stud 266 which is movable by the piston 203 of a solenoidoperated pneumatic cylinder 210 through a system of levers 212. This leverage is pivoted on the same shaft 138 as the lever system which operates the cutter, and is attached to piston 268 through a connector 214 and a slide 216 operating in a track 218. Adjustment of the height of the clamp 290 to provide for clearance of different thicknesses of stock is accomplished with a shouldered adjustment nut 220 threaded upon the end of stud 2'96 and engageable with a block 222 attached to the frame of the machine.

Feed.-The feeding mechanism is shown in plan view in FIGS. 5 and 6, and in elevation in FIG. 8.

As explained previously, and as shown in FIG. 5, the stock material from which the laminations are being formed is fed in a continuous strip 36 which is pulled by the feeding mechanism from a roller (not shown) on a stand in a convenient location proximate the machine. The dimension of each side of the lamination is determined by the length of stock which is fed across die plate 40 by the rollers 43 between successive bending or cutting operations.

The mechanism 48 which feeds the stock material includes, in the specific embodiment under description, :1 top split roller assembly 48a, and a bottom roller 48b. The split roller device 48a is employed to aid in keeping the stock material feeding in a straight line through the work station 38. The complete roller assembly is driven by an appropriate gear mechanism (not shown) connected to shaft 5t which is supported by pillar blocks 51. As has been explained, the degree of rotation imparted to the shaft 50 for each successive feeding operation determines the length of stock material measured across the die plate 49 for that operation and consequently the longitudinal dimension of the particular side of the lamination being formed.

For a three-sided lamination such as the one shown in FIG. 1, three feed controls and their associated mechanisms are used to provide an independent means for measuring each side of the lamination. In accordance with a programmed cycle controlled by the circuitry and associated mechanism shown in FIGS. 17a and 17b, each of these feed control mechanisms successively turns the shaft 54 and, therewith, shaft 50, to which it is joined by coupling 52, to impart a desired degree of rotation to the rollers 43 and a measured. feed to the stock material.

As shown in PEG. 6, each feed comprises a gear 53 connected by a one way clutch 56 to the shaft 54 and operated by a rack 60. The rack is moved by the piston 224 of a solenoid controlled pneumatic cylinder 226, to which it is attached by a connector 228, and slides in a track 230 which forms a part of the general frame structure of the machine.

When the piston 224 pulls the rack 60 downward to the position shown in FIG. 8, the rack turns gear 58 in a clockwise direction imparting a similar turn to shafts 54 and 50. Shaft 59 thereupon, through a geared connection (not shown), reverses the clockwise motion and causes rollers 48 to feed stock material 36 across the die plate 40. On the return stroke, when piston 224 is forced from the cylinder 226 and the rack 60 is thereby pushed upward, the one way feature of clutch 56 enables the gear 58 to turn in a counterclockwise direction without imparting any of its motion to shaft 54 or feeding rollers 48. Thus, the mechanism is capable of feeding a length of stock material each time the rack 69 associated with any one of the three feeds accomplishes a downward stroke. The manner in which the length of material fed by this stroke is measured to a critical dimension, variable automatically for successive laminations, is explained in the following description of the increment control mechanism.

Increment c0/ztr0l.The increment control mechanism 9 is shown in plan view in FIG. 6, and some of its parts in elevation in FIGS. 8-11.

Referring to FIG. 6, a separate increment control rack 62 for each of the three feeds is movable in forward and return traverses in a track 231 by a gear 64, which is turned in a clockwise or counterclockwise direction by the clutch 56 each time the feed operating rack 60 makes adownward or upward stroke, respectively. The limits of the forward and reverse traverses of rack 62 are defined by a rear stop 232 and an adjustable front stop comprised by the nut 66 on threaded increment adjustment shaft 68. A buffer 62a protects the end of rack 62 where it contacts the stop nut 66.

On its downward or feeding stroke, rack 60 turns clutch 56 and gear 64 in a clockwise direction. This moves rack 62 toward stop 252 and the stroke ends when the rack hits the stop. On the return or upward stroke of rack 60, since clutch 56 is connected to shaft 54 only for driving in a clockwise direction, shaft 54 and its associated feeding mechanism are stationary; but, gear 58, through clutch 56, turns gear 64 to move rack 62 until butter 62a strikes the adjustable stop nut 66.

In this manner, gear 58 is operated by rack 60* to turn shaft 54 and feed stock material 36 for a number of degrees of rotation of shaft '54, and consequently a length of stock material, which is measured by the traverse of rack 62 from contact with the adjustable location of stop nut 66 to contact with fixed stop 232. An explanation of how the location of stop nut 66 on the increment control shaft 68 i adjusted between feed strokes in order to change the length of this traverse, and consequently the dimensions of each side of successive laminations follows.

In FIG. 9 a portion of the adjustable stop nut 66 is shown in a side elevation, along with its associated increment control shaft 68 and the mechanism whereby the shaft 68 is turned so that its threads move the nut 66 forward or backward in a track 234 attached to the structural framework of the machine.

The shaft 68 is turned in measured increments by a clutch 70 connected, through a main chain 236 and an appropriate sprocket mechanism to an increment control shaft 72. The extent to which this shaft 72, and consequently shaft '68, is turned for each incremental adjustment is determined by the degree of rotation imparted to increment clutch 74 by increment control rocker 7 6' which is operated by a solenoid controlled pneumatic cylinder 238 having its piston 240 connected through suitable linkage 242 to one end of the rocker.

When the solenoid 238 withdraws its piston 240 to pull rocker 76 and impart a counterclockwise motion to clutch 74 and shaft 72, shaft 68 is similarly turned by belt 236 and clutch 70 to move the nut 66. The amount of turn imparted is determined by the position of increment limiting screw 78 in the path of movement of rocker 76. This limiting screw may be turned by a handle 244 to set it to the desired position relative to rocker 76. The proper setting is determined by referencing pointer 246 against a scale on upright 248. This setting is maintained by a serrated collar and spring loaded detent combination 250. The incremental increase to which the limiting screw 78 is set is generally that which will permit rocker 7-6 to move through an arc sufficient to impart to shaft 68 sufficient turn to move stop nut 66 a distance calculated to permit rack 62 an increase in traverse sufficient to enable rack 60 to turn shaft 54 and feed rollers 48 an increased distance through an are which will increase the length of stock material fed since the last operation controlled by this particular feeding mechanism by a distance corresponding to the thickness of the stock material used. On the upward stroke of piston 240 and corresponding clock-wise thrust of rocker 76, clutch 74 is adapted to rotate free on shaft 72 so that no motion is imparted to shaft 68.

Zero setting.-As explained above, each of the three feed mechanisms shown control the dimension of a separate one of the three-sided laminations shown in FIGS. 1-3. In order to accomplish the proper initial setting of the adjustable stop nuts 66 of each control mechanism so that the first lamination of each series comprising a separate core will have the proper dimensions, a zeroing operation is performed. The mechanism for accomplishing this is located at the front of the machine. It is shown in plan view in FIG. 6 and in side and front elevations respectively in FIGS. 9 and 11.

The zero settings are achieved by turning shaft 68 in a counterclockwise direction, as viewed in 'FIG. 11, to move the respective stop nuts 66' along shaft 68 and push each forward to the proper setting for the smallest desired dimension for the side which it controls.

As a preliminary requirement of this zeroing operation, clutch 70 is disengaged from shaft '68 so that the turning of the shaft to achieve zero setting will not affect the increment control mechanism. This is accomplished, in the machine under description, by providing that clutch 70 be electrically controlled so that it can be disconnected from shaft 68 when desired by appropriate electrical signals from the programmed control system.

Zeroing is effected by rotating a shaft 252 connected as an extensionto the increment control shaft 68 until the stop nuts '66 are in zero position. Each shaft 252 has a clutch 84 with a sprocket 254 connected by a chain 82 to a sprocket 256 on zeroing motor which is thus enabled to turn these shafts. Also connected to each shaft 252 is an increment plate 258 having a stop arm 260 with a stop abutment area 262. The area 262 is engageable with a slidable step 264 carried by a slide 266 connected by a linkage 268 to the stop nut 66. Suitable fittings 270 attached to the framework of the machine are provided so that the slide may move forward and backward as the stop nut '66 is adjustably positioned.

Slide 266 is divided into a front portion 266a, which carries the slida'ble stop 264, and a rear portion 266b which is attached to the stop nut 66. The stop 264 may be movable along slide 266, or the two portions 266a and 266b may be slidably fitted to one another so that the overall slide is expandable. By either technique, the point of contact between abutment 262 and stop 264 can be controlled to correspond with the location of stop nut 66 desired for the initial dimension of the first lamination. This setting can be facilitated by referencing a scale 271 on the slide 266 against a pointer 272 mounted on the framework of the machine. For this purpose, scale 2.7-1 may be calibrated in dimensions corresponding to those in which the different sides of the laminations are measured.

This machine works within very precise tolerances to measure the various dimensions of the laminations with exactitude. Therefore, in order that the engagement of abutment surface 262 with stop 264 may be set to a location determined by degrees of turn of the shaft 68 instead of full turns, the arm 260 is made adjustable radially of the increment plate 258, by means of a bind block 274.

The zeroing clutches 84 are of the friction type and electrically controllable. They are energized to engage their respective shafts 252 when the zeroing motor 80 starts to operate. Because each clutch 84 is capable of slipping relative to its shaft 252 it is possible to provide different initial settings for each of the controlled dimensions of the lamination and to vary the relative lengths of these dimensions as desired. Each of the three feed control mechanisms comes to rest as its adjustable stop nut 66 is cycled to zero; and the zeroing motor continues to operate until all zero settings are accomplished. The motor is stopped when a lug 276 on chain 82 comes into contact with the operating arm 278 of a micro-switch 280'.

Programmed Control System.The operating sequence of the various parts of the machine is programmed by an electrical control system shown schematically in FIGS. 

1. FOR FABRICATING A LAMINATED CORE FOR AN ELECTROMAGNETIC INDUCTOR, A METHOD OF MANUFACTURING A (-SHAPED LAMINATED MEMBER FOR A CORE ASSEMBLY COMPRISING THE STEPS OF: PREPARING A FIRST THREE SIDED, (-SHAPED, LAMINATE MEMBER BY FEEDING A CONTINUOUS STRIP OF CORE MATERIAL IN A FIRST SERIES OF FIRST, SECOND AND THIRD MEASSURED DISTANCE, BENDING SAID MATERIAL IN A SUBSTANITLLY 90* ANGLE IN A GIVEN DIRECTION AT THE END OF SAID FIRST MEASURED DISTANCE, BENDING SAID MATERIAL IN A SUBSTANTIALLY 90* ANGLE IN THE SAME GIVEN DIRECTION AT THE END OF SAID SECOND 